AbstractThe use of saphenous vein for coronary artery bypass grafting is an established surgical revascularization strategy in patients with ischemic heart disease. However, 30-50% of venous grafts fail within 10 years. Vein graft failure involves intimal thickening as a result of endothelial cell (EC) damage and inflammation which promotes vascular smooth muscle cell (VSMC) de-differentiation, migration and proliferation. Proline Rich Homeodomain (PRH) protein is a transcription factor required for growth and differentiation. We investigated whether adenovirus-mediated delivery of non-phosphorylated PRH (PRH-CC) protein attenuates VSMC proliferation without detrimental effects on EC.
We observed that overexpression of Ad: PRH S163C:S177C in VSMCs significantly inhibited proliferation, migration and promoted the contractile phenotype. Importantly, we also showed that overexpression of Ad: PRH S163C:S177C impaired carotid artery ligation induced neointimal proliferation and thickening. Importantly, Ad: PRH S163C:S177C did not significantly affect HSV endothelial cell (HSVEC) proliferation, migration, and apoptosis. However, interestingly, the expression of TNFα-induced vascular cell adhesion molecule 1 (VCAM-1) and Intercellular Adhesion Molecule 1 (ICAM-1) proteins were significantly reduced in Ad: PRH S163C:S177C treated HSVECs and was associated with significantly reduced monocyte adhesion. Other inflammation-related molecules such as interleukin-6 (IL-6) and monocyte chemotactic factor-1 (MCP-1) measured by ELISA were also significantly attenuated, indicative of suppression of a pro-inflammatory response to TNFα. Using Next Generation Sequencing, we reveal Signal transducer and activator of transcription 1 (STAT-1) and Histone deacetylase 9 (HDAC-9) as novel targets of PRH which were validated by in vitro and in vivo analyses.
We observed that PRH-CC attenuated VSMC proliferation and migration and enhanced VSMC differentiation, whilst promoting the endothelial repair and anti-inflammatory properties. Moreover, this study identified novel mechanisms that beneficially regulate VSMC behaviour and preserve the endothelial function. These findings have the potential to translate into novel therapeutics for the reduction of late vein graft failure in the future.
|Date of Award||11 May 2021|
|Supervisor||Sarah J George (Supervisor)|